Hi, Consider two fixed points A and B in a frame S. In this frame a person P moves towards the point A and does an event EA. After that, this person moves to the point B and does an event EB. Based on Lorentz's transformations, it is very easy to find a frame S' where events EA and EB occur simultaneously. The problem is that this leads to that the person P exists in both positions A and B simultaneously! (according to S'). How is this possible?